In recent cosmetics and food industries, there are growing fears about health hazards of materials of animal origin, and regulations for such materials are being tightened, which gives rise to stronger interest in materials of plant origin. On the other hand, serious problems are arising, such as acceleration of ageing by oxidation of active oxygen taken into or generated within the body, and skin coloration by UV rays or carcinogenicity thereof.
For example, food, cosmetics, and the like articles are suffering from oxidation or peroxidation of oils and fats contained in various materials thereof, caused by atmospheric oxygen during manufacture, processing, storage, or preservation of such articles. Unsaturated fatty acids contained in oils and fats, such as linoleic and linolenic acids, are known to be particularly prone to peroxidation by atmospheric oxygen to generate lipid peroxides, free radicals, or even carcinogenic substances. Oxidation and peroxidation cause change of the products in appearance, such as coloration, discoloration, denaturalizaton, or abnormal odor, or in quality, such as decrease in effective nutritional value. Further, denaturalization may cause generation of toxic substances, which results in deterioration of product quality.
In order to inhibit such oxidation and peroxidation of unsaturated fatty acids, and to prevent deterioration of product quality, various antioxidants have conventionally been used. Antioxidants act on peroxide radicals, which are generated in oxidation, to terminate chain oxidation, or alternatively act on free radicals to terminate oxidative reaction. Commonly used antioxidants are synthetic antioxidants, such as butylhydroxyanisol (BHA) and butylhydroxytoluene (BHT). Recently, however, effects and safety of synthetic antioxidants on the human body have come to be questioned as their use expands, and consumers are presenting growing rejections. Further, synthetic antioxidants are oil soluble, and thus are hard to use in aqueous solutions.
On the other hand, as natural antioxidants of high safety, natural vitamin E (α-tocopherol), vitamin C, and the like are known. However, the properties of these natural antioxidants are in either extreme, i.e., either extremely fat- or water-soluble, so that their applications are naturally limited. The natural antioxidants also have disadvantages in that their activity cannot be maintained stably for a prolonged period of time.
There is thus a strong demand for natural antioxidants having strong antioxidative activity, high water-solubility, and long-termstability in antioxidative activity.
Pigmentation, such as skin coloration or age spots, is caused by intrinsic factors such as metabolic defects in living organism, and extrinsic factors such as UV rays. Pigmentation caused by the latter extrinsic factors is more common, wherein UV rays stimulate melanocytes to activate the same, which in turn activates tyrosinase to induce skin pigmentation. It is known that inhibition of the melanocyte activity to thereby inhibit generation of tyrosinase and melanin pigment results in prevention of pigmentation such as skin coloration or age spots. In the cosmetic industry, much importance has been placed on development of substances having whitening effects, and various whitening agents have been developed. In addition, UV dose is recently increasing due to ozone depletion or other factors. This further stimulates consumer's demand for measures against UV, and safe and effective whitening agents.
Collagen and hyaluronic acid are known to have effects on moisture retaining property, softness, and elasticity of skin. Collagen constitutes 90% of dermis of skin and is distributed all over the dermis to give appropriate elasticity and strength to the skin. Hyaluronic acid is widely distributed over living organisms such as skin, synovial fluid, corpus vitreum, ligament, and the like, and contributes in skin to cell adhesion, cell protection, formation of skin tissues, retainment of tissue moisture, and maintenance of softness. Collagen and hyaluronic acid are known to be decomposed in vivo with enzymes called collagenase and hyaluronidase, respectively. It is said that, when these enzymes decompose collagen and hyaluronic acid to decrease their amounts, skin loses moisture and tension, and develops wrinkles and sagging, which are typical symptoms of skin ageing.
In expectation of anti-ageing and anti-wrinkle effects on skin, it is proposed to add substances that inhibit activities of these enzymes, to skin preparations for external use and various cosmetics, and various collagenase inhibitors and hyaluronidase inhibitors have been developed to date.
Camu camu fruit, which is recognized as a vitamin C-rich plant like acerola fruit, is commercially sold in South America as cosmetics or food, and is recently imported and sold also in Japan as a food material. Since the major component of camu camu fruit is vitamin C, its extract finds applications in antioxidants, moisture retainers, and whitening agents (for example, JP-9-221429-A, JP-11-246336-A, JP-2000-327549-A, JP-2000-327550-A, and JP-2001-31558-A).
However, only the pulp of camu camu fruit, which has a high vitamin C content, is used in cosmetics and food, and the seeds, which has only a slight vitamin C content, hardly find effective use and are discarded.